1. Field of this Invention
This invention relates to a process for the production of 4-alkoxyacetoacetic esters.
2. Prior Art
4-ethoxyacetoacetic ester has been produced by reaction of bromoacetic ester and ethoxyacetic ester with zinc [J. Amer. Chem. Soc., 68, (1946), 2392] or by reaction of ethoxyacetic ester with acetic ester in the presence of sodium [Chem. Abstr., 43, (1949), 2625e]. 4-methoxyacetoacetic ester has been produced by condensation of methoxyacetylchloride with malonic acid ethyl tert.-butyl ester with subsequent saponification and decarboxylation [J. Amer. Chem. Soc., 70, (1948), p. 500]. The yields obtained according to these processes are in the neighborhood of 11, 21 or 40 percent, respectively.
Experiments designed to produce 4-ethoxyacetoacetic ester from 4-chloroacetoacetic ester with equimolar quantities of Na-alcoholates in alcohol failed. Instead of the anticipated 4-ethoxyacetoacetic ester, succinyl succinic acid diethyl ester was obtained [Bull. Soc. Chim. France, 4th series, 29, (1921), pp. 402-406].
Swiss Pat. No. 562,191 teaches the successful production of 4-alkoxyacetoacetic esters from 4-haloacetoacetic esters with alkali alcoholates whenever the operation is conducted in a mixture of an alcohol and an aprotic solvent with high dielectricity constant, preferably dimethyl sulfoxide, at a temperature of 15.degree. to 30.degree. C. The disadvantages of such process are that reaction times of 24 to 72 hours are required and that the reaction must be carried out in a large quantity of the solvent mixture.
T. Kato, J. Chem. Soc., Perkin I, 529, (1979), teaches the production of 4-ethoxyacetoacetic ester from 4-bromoacetoacetic ester. According to this paper, one equivalent of 4-bromoacetoacetic ester is reacted with 2.2 equivalents of sodium ethylate. Large quantities of ethanol serve as the solvent, but the yields of 47 percent are very modest.